Littlezor
The littlezor split from the linzor as they moved northward through Hydro and into Barlowe, connected by a common shallow sea. They found a complete dearth of any fauna larger than a knightworm. While their close relatives, the pallazors and lungers, had responded with increased sizes, the littlezor instead shrank drastically, filling the vacant niche of small generalist herbivore.
The adults have become slightly more terrestrial in focus, though they're still capable of swimming. They retain their gills (though with fewer slits) and the membranes on their limbs. However, their anal arm now retains its hand into adulthood, rather than developing into a fin. They generally only venture into water to avoid particularly hot weather or to cross a stream. After all, the presence of lungers makes the water rather more dangerous than it had been for their ancestors.
Another response to the lungers is that their dorsal sail has lost its membrane. Its spines have become hard and sharp, used as spikes to deter predators.
Their smaller size made it more difficult to eat some of the crystal flora that had been the mainstay of their diet. This still makes up a big portion of their food, mostly leaf-crystals and seeds, but they've branched out into leafstars and photosagnian flora as well. This is reflected in their purple coloration, better-adapted for blending among purple undergrowth. Additionally, they no longer required such robust crunching jaws. The lower jaw is still quite powerful, but their face is notably less blocky and their lateral mandibles are thinner.
Littlezors maintain a yearly lifecycle. Larvae transition into adulthood in the springtime. Adults mate throughout the warm months and give birth in the autumn. In the more seasonal parts of their range, adults often die in the winter; elsewhere, they may survive to a second year. Either way, larvae grow in the ocean throughout the winter, where temperatures are milder and they won't freeze.
Their physical form has undergone little change otherwise. As larvae, they have radial symmetry, which becomes bilateral as they age. They have three legs, four lungs, and four gills. Their blood is magenta and uses hemerythrin as its pigment.